Communication control apparatuses such as an Ethernet (registered trademark) switch have conventionally been employed in networks such as a wide-area Ethernet and a local area network (LAN), for controlling data transfer. Such a communication control apparatus has a plurality of ports for connection to a server or other communication control apparatuses.
The communication control apparatus holds a learning table containing sets of a port number and an associated media access control (MAC) address of an apparatus connected via a port identified by the port number, and transfers received data to a destination in accordance with the learning table.
An example of a learning process regarding the learning table performed by the communication control apparatus will be discussed. Here, it is assumed that the communication control apparatus receives data X via a port P1 (the “port P1” refers to a port identified by a port number “P1”), that the data X has an address MAC_A as a source address and an address MAC_B as a destination address, and that the address MAC_A has not yet been registered in the learning table.
In this case, the communication control apparatus registers the source address MAC_A in association with the port number P1. In the case where the destination address MAC_B has been registered in the learning table, the communication control apparatus transmits the data X via the port identified on the basis of the learning table. In the case where the destination address MAC_B has not been registered in the learning table, the communication control apparatus floods the data X via the ports other than the port P1.
Thus, the communication control apparatus may associate the address MAC_A with the port P1, and when data destined for the address MAC_A is received via another port, the communication control apparatus may transmit that data via the port P1, instead of flooding.
Upon detecting a trouble at a port P2, the communication control apparatus identifies, on the basis of the learning table, addresses of the apparatuses connected to the port P2 and floods, to all the ports, a flush message containing the identified addresses as addresses of apparatuses which may be affected by the trouble. Upon receiving the flush message, other communication control apparatuses delete, from the learning table, information related to the addresses contained in the flush message, and floods the received flush message via all the ports other than the port via which the flush message has been received.
International Publication No. 2008/111128 and Japanese Patent No. 4473700 disclose related techniques.